Target practice ammunition of thermoplastic material



Sept. 1, 1964 w. MAURER ETAL 3,146,712

TARGET PRACTICE AMMUNTTTCN 0F THERMOPLASTIC MATERIAL FiledApril 12. 19er INVENTORS WALDEMAR MAURER KARL KOCH EM/L EIS/NGER United States Patent Office` Patented Sept. l, 1964 3,146,712 TARGET PRACTICE AMMUNITIGN F THERMGPLASTIC MATERIAL Waldemar Maurer, Karlsruhe-Durlach, and Karl Koch and Emil Eisinger, Berghausen, Baden, Germany, assiguors to Dynamit Nobel Aktiengesellschaft, Troisdorf, Bezirk Cologne, Germany, a corporation of Germany Filed Apr. 12, 1961, Ser. No. 102,615 Claims priority, application Germany Apr. 16, 1960 5 Claims. (Cl. 102-41) The present invention rela-tes to target practice ammunition of thermoplastic material, and more particularly to a target practice ammunition cartridge comprising an integrally connected cartridge shell and projectile having a predetermined place of fracture therebetween, said projectile having a rearwardly directed hollow portion.

It is known to produce blank cartridges of various plastic materials. Accordingly, a projectile has been proposed for practice ammunition purposes which consists of a synthetic resin mass. Disadvantageously, however, projectiles of the foregoing 4type disintegrate, due to the adverse effect of air resistance, shortly after leaving the barrel of the weapon fro-m which they are fired.

It is an object of the present invention to overcome the foregoing disadvantage and to provide target practice ammunition of thermoplastic material, including a cartridge shell and a projectile integrally connected and having a predetermined place of fracture therebetween.

It is a further object of the present invention to provide a target practice ammunition cartridge of thermoplastic material wherein the thermoplastic material has a density of below 1.

Other and further objects of the invention will become apparent from a study of the within specification and the accompanying drawing, in which the gure illustrates a target practice ammunition cartridge in accordance with the invention shown in partial section to indicate details of construction.

It has been found in accordance with the present invention that an effective, simple and economical target practice ammunition cartridge of thermoplastic material may be provided which comprises means defining a cartridge shell and projectile therefore integral therewith, and means defining a predetermined place of fracture between the projectile and cartridge shell. The projectile is provided with a bottom end, adjacent to the cartridge shell, having a hollow recess defined therewithin. Significantly, the integrally connected cartridge shell and projectile are made of thermoplastic material having a density below 1. The preferred types of thermoplastic material used in accordance with the invention include polyethylene and polypropylene having a density below 1, and more particularly Ziegler-type low pressure polyethylene and polypropylene.

The cartridge shell, of course, will be preferably hollow in structure such that the hollow recess in the rearward portion of the projectile will register with the hollow portion of the cartridge shell. Advantageously, an annular groove will be present `along the inner Wall of the cartridge, defining the predetermined place of fracture of the integral cartridge shell and projectile upon firing the cartridge from a suitable weapon. Therefore, the present invention provides a cartridge arrangement having a low projectile weight, affording a positive and clean separaion of the projectile from the cartridge shell upon firing and ensuring a good trajectory stabilization of the projectile after leaving the barrel.

Speciiically, for example, a projectile composed of polyethylene suitable for a pistol cartridge having a calibre of 9 mm. parab. has a weight of only 0.4 g., while the same projectile made from metal weighs 8 g. Such a polyethylene projectile upon firing at a gas pressure of only 420 atmospheres execess presure (guage) has a muzzle velocity of about 500 m./sec., whereas the same projectile made from metal at a gas pressure of 2400 atmospheres excess pressure (guage) possesses a muzzle velocity of only 340 m./ sec. Because of the high initial velocity of the polyethylene projectile of the present invention, the precision over short distances is very good. In consequence of the low weight, the projectile, however, over greater distances decreases very rapidly in speed and energy. For example, the velocity vlag, amounts to about only 320 m./sec. for a polyethylene plastic projectile of 4the foregoing type.

Therefore, a rapidly decreasing trajectory of the plastic projectile of the present invention will positively occur whereby comparatively short distances will be achieved with the projectile. Thus, a maximum travel of a plastic projectile of the foregoing type having a calibre of 9 mm. parab. amounts to about m., whereas a similar projectile composed of metal possesses a maximum distance of travel of about 1500 m.

In the same way, for projectiles having a calibre of 7.65 mm. Brow., where the same are made from thermoplastic material in accordance with the invention, the maximum distance of travel amounts to about 70 m., while the same projectile made from metal will travel about 1200 m. Similar observations are present with respect to rie cartridges wherein a thermoplastic pointed bullet or projectile in accordance with the invention, having a calibre of 7.62 mm., shows a maximum distance of travel of about 300 rn., while the distance when the same projectile is made from metal amounts to about 4000 m.

As will be readily appreciated from the foregoing comparisons with respect to the thermoplastic projectile of the invention and conventional metal projectiles, the cartridge of the present invention is most advantageous for use as target practice ammunition where the need or desire for tiring only o-ver short distances is obvious.

By providing a hollow recess in the projectile bottom portion or rearward por-tion closest to the top portion or forward portion of the cartridge shell, the propellent gas pressure generated within the barrel of the weapon will be effectively utilized for improving the sealing of the projectile against the barrel wall during its passage through the bore of the gun.

It can be readily appreciated that the danger range in shooting weapons with cartridges in accordance with the invention may be kept substantially smaller than that involved in shooting with conventional cartridges, especially those possessing a heavy metal projectile of the usual type. Consequently, where the thermoplastic cartridges of the present invention supplant the customary cartridges now used, very substantial simplifications in planning, designing and constructing shooting range in stallations may be achieved. This is true since inherently a plastic cartridge of the type contemplated by the present invention will only be eifective over comparatively short distances and, therefore, will not involve a peril to life and limb beyond such short distances. Accordingly, less troublesome safeguards will be necessary with respect to the shooting gallery or shooting range and, of course, a smaller perimeter of danger area will be involved.

The accompanying ligure illustrates a thermoplastic cartridge of the invention such as, for example, that made from polyethylene plastic. The projectile 1 and cartridge shell 2 are constructed in one piece and have therebetween a predetermined place of fracture 5 defined by an internal annular groove 3 located at the bottom end 1b of projectile 1 and the top` end 2a of cartridge shell 2. Groove 3 ensures a clean separation of the projectile thick wall 6 from the cartridge shell thin walled top end 2a upon ring of the weapon. The plastic projectile 1 is provided with a hollow recess 4 extending inwardly from towards the top pointed end la thereof, said recess 4 terminating at about the middle part of the projectile. Of course, the cartridge shell 2 is constructed in a hollow manner so that the same may contain the powder charge which upon detonation forces a clean separation of the projectile 1 from the shell 2 at annular groove 3 where the interconnecting wall 5 between projectile 1 and cartridge shell 2 is thinnest, and by reason of the gases generated the desired velocity is imparted to the projectile. It will be appreciated that since projectile 1 is provided with a hollow recess 4 directed towards its bottom or rearward end, such gases will be exerted outwardly upon the surrounding wall of recess 4, causing an eiective compression of the outer surface 7 of projectile 1 thereat against the adjacent portions of the barrel of the weapon from which the projectile is tired so as to produce an elfective seal between said projectile 1 and adjacent barrel wall.

It will be appreciated that in addition to polyethylene, any other suitable thermoplastic material having a density below 1 may be used for constructing the cartridge of the invention, such as polypropylene plastic material.

What is claimed is:

1. Target practice ammunition of thermoplastic material comprising means defining a cartridge shell and projectile therefor completely integral therewith along their com-mon extent, and means dening a predetermined place of positive and clean fracture in a plane passing completely transversely between said projectile and said cartridge shell, said projectile having a bottom end adjacent to the cartridge shell provided with a hollow recess defined therein.

2. Target practice ammunition according to claim 1 wherein the integral cartridge shell and projectile are the bottom end 1b of the projectile mon extent, said projectile having a pointed top end and a bottom end adjacent to the cartridge shell top end and sealing off said shell top end, said projectile bottom end having a hollow recess centrally defined therein extending toward said projectile pointed top end and terminating at about the middle of said projectile, the interior of the hollow cartridge shell communicating directly with the hollow recess of said projectile, means defining an annular groove portion of decreased connection being provided in a plane passing completely transversely between said cartridge shell and said projectile serving as a predetermined place of positive and clean fracture between said shell and said projectile upon firing the cartridge, said cartridge being composed completely and homogeneously throughout of thermoplastic material having a density below about 1.

4. Target practice cartridge according to claim 3 wherein said thermoplastic material is polyethylene.

5. Target practice cartridge according to claim 3 wherein said thermoplastic material is polypropylene.

References Cited in the le of this patent UNITED STATES PATENTS UMTED STATES PATENT OFFICE CERTIFICATE 0E CORRECTION Patent Noa 3i 146,712 September lq 1964 Waldemar Maurer et al,

It is hereby certified that error appears in the above numberedipat-v ent requiring correction and that the said Letters Patent should read as corrected below.

Column l line 43?` for "therefore" read therefor column 2Y line 699 after "shell" insert or casing column 3, line 30 beginning with "L Target practice ammunition" strike out all vto and including "material is polypropylene", in 'line 28 column 4, and insert instead the following:

lB Target practice cartridge of thermoplastic material comprising means defining a thermoplastic cartridge casing and means defining a thermoplastic projectile for said casingv said casing and projectile being completely integral with one another along their common abutting extentV and means defining a predetermined place of positive and clean fracture in a plane passing completely transversely between said casing and projectile, Said projectile having a bottom end provided with a hollow recess defined therein adjacent to the cartridge casingo 2. Target practice cartridge according to claim l wherein the integral cartridge casing and projectile are both Amade of thermoplastic material having a density below about l 3 Target practice cartridge of thermoplastic material comprising means defining a hollow thermoplastic cartridge casing having a bottom end portion and an open top end portion and defining an internal aperture for containing a propelling charge therewhithin and a thermoplastic projectile for Said icart ridge casing completely integrally connected therewith along their common extent said projectile having a pointed top end and a bottom end adjacent to the cartridge casing top end portion and sealing off said casing top end portionq said projectile bottom end having a hollow recess centrally defined therein extending toward said projectile pointed top end and terminating at about the middle of said projectileq the interior of the hollow cartridge casing communicating directly with the hollow recess of said pro jectile, means defining an annular groove portion of decreased connection being provided in a plane passing completely transversely between said cartridge casing and said projectile serving as a predetermined place of positive and clean fracture between said casing-and said projectile upon firing the cartridgey said-earbridge being composed completely and homogeneously f` throughout of thermoplastic material having al--density below about l.

4., Target practice cartridge according tov claim 3 wherein said thermoplastic material is polyethylene.

5. Target practice cartridge according Ato ;claim 3 wherein said thermoplastic material is polypropylene.

Signed and sealed this 23rd day of February 1965.

(SEAL) Attest:

ERNEST W SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents UNITED STATES PATENT oEEIcE CERTIFICATE 0F CORRECTION Patent No., 3, 146,712 September l, 1964 Waldemar Maurer et al lt is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column l, line 13, for "therefore" read therefor column 2, line 69, after "shell" insert or casing j column 3, line 3C), beginning with "1. Target practice ammunition" strike out all to and including "material is polypropyleneo in line 28, column 1, and insert instead the following:

l Target practice cartridge of thermoplastic material comprising means defining a thermoplastic cartridge casing and means defining a thermoplastic projectile for said casing, said casing and projectile being completely integral with one another along their common abutting extent, and means defining a predetermined place of positive and clean fracture in a plane passing completely transversely between said casing and projectile, said projectile having a bottom end provided with a hollow recess defined therein adjacent to the cartridge casing,

2. Target practice cartridge according to claim l wherein the integral cartridge casing and projectile are both made of thermoplastic material having a density below about lu 3 Target practice cartridge of thermoplastic material comprising means defining a hollow thermoplastic cartridge casing lhaving a bottom end portion and an open top end portion and defining an internal aperture for containing a propelling charge therewhithin and a thermoplastic projectile for Said cart ridge casing completely integrally connected therewith along their common extent, said projectile having a pointed top end and a bottom end adjacent to the cartridge casing top end portion and sealing off said casing top end portion, said projectile bottom end having a hollow recess centrally defined therein extending toward said projectile pointed top end and terminating at about the middle of said projectile, the interior of the hollow cartridge casing communicating directly with the hollow recess of said projectile, means defining an annular groove portion of decreased connection being provided in a plane passing completely transversely between said cartridge casing and said projectile serving as a predetermined place of positive and clean fracture between said casing-aand said projectile upon firing the cartridge.,l said-ea-,.rt ridge being composed completely and homogeneously 7" throughout of thermoplastic material having a `density below about l. f

4., Target practice cartridge according tov cl-aim 3 wherein said thermoplastic material is polyethylene 5. Target practice cartridge according yto claim 3 wherein said thermoplastic material is polypropylene.

Signed and sealed this 23rd day of February 1965,.

(SEAL) Attest:

ERNEST W., SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. TARGET PRACTICE AMMUNITION OF THERMOPLASTIC MATERIAL COMPRISNG MEANS DEFING A CARTRIDGE SHELL AND PROJECTILE THEREFOR COMPLETELY INTEGRAL THEEWITH ALING THEIR COMMON EXTENT, AND MEANS DEFINING A PREDETERMINED PLACE OF POSITIVE AND CLEAN FRACTURE IN A PLANE PASSING COMPLETELY TRANSVERSELY BETWEEN SAID PROJECTILE AND SAID CARTRIDGE SHELL, SAID PROJECTIVE HAVING A BOTTOM END ADJACENT TO THE CARTRIDGE SHELL PROVIDED WITH A HOLLOW RECESS DEFINED THEREIN. 